Targeting TGFß-activated kinase-1 activation in microglia reduces CAR T immune effector cell-associated neurotoxicity syndrome.

Cancer immunotherapy with chimeric antigen receptor (CAR) T cells can cause immune effector cell-associated neurotoxicity syndrome (ICANS). However, the molecular mechanisms leading to ICANS are not well understood. Here we examined the role of microglia using mouse models and cohorts of individuals with ICANS. CD19-directed CAR (CAR19) T cell transfer in B cell lymphoma-bearing mice caused microglia activation and neurocognitive deficits. The TGFß-activated kinase-1 (TAK1)-NF-κB-p38 MAPK pathway was activated in microglia after CAR19 T cell transfer. Pharmacological TAK1 inhibition or genetic Tak1 deletion in microglia using Cx3cr1CreER:Tak1fl/fl mice resulted in reduced microglia activation and improved neurocognitive activity. TAK1 inhibition allowed for potent CAR19-induced antilymphoma effects. Individuals with ICANS exhibited microglia activation in vivo when studied by translocator protein positron emission tomography, and imaging mass cytometry revealed a shift from resting to activated microglia. In summary, we prove a role for microglia in ICANS pathophysiology, identify the TAK1-NF-κB-p38 MAPK axis as a pathogenic signaling pathway and provide a rationale to test TAK1 inhibition in a clinical trial for ICANS prevention after CAR19 T cell-based cancer immunotherapy.

Gadolinium contrast agents: dermal deposits and potential effects on epidermal small nerve fibers.

Small fiber neuropathy (SFN) affects unmyelinated and thinly myelinated nerve fibers causing neuropathic pain with distal distribution and autonomic symptoms. In idiopathic SFN (iSFN), 30% of the cases, the underlying aetiology remains unknown. Gadolinium (Gd)-based contrast agents (GBCA) are widely used in magnetic resonance imaging (MRI). However, side-effects including musculoskeletal disorders and burning skin sensations were reported. We investigated if dermal Gd deposits are more prevalent in iSFN patients exposed to GBCAs, and if dermal nerve fiber density and clinical parameters are likewise affected. 28 patients (19 females) with confirmed or no GBCA exposure were recruited in three German neuromuscular centers. ISFN was confirmed by clinical, neurophysiological, laboratory and genetic investigations. Six volunteers (two females) served as controls. Distal leg skin biopsies were obtained according to European recommendations. In these samples Gd was quantified by elemental bioimaging and intraepidermal nerve fibers (IENF) density via immunofluorescence analysis. Pain phenotyping was performed in all patients, quantitative sensory testing (QST) only in a subset (15 patients; 54%). All patients reported neuropathic pain, described as burning (n = 17), jabbing (n = 16) and hot (n = 11) and five QST scores were significantly altered. Compared to an equal distribution significantly more patients reported GBCA exposures (82%), while 18% confirmed no exposures. Compared to unexposed patients/controls significantly increased Gd deposits and lower z-scores of the IENF density were confirmed in exposed patients. QST scores and pain characteristics were not affected. This study suggests that GBCA exposure might alter IENF density in iSFN patients. Our results pave the road for further studies investigating the possible role of GBCA in small fiber damage, but more investigations and larger samples are needed to draw firm conclusions.

Primary cilia contribute to the aggressiveness of atypical teratoid/rhabdoid tumors.

Atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant brain tumor in infants that is characterized by loss of nuclear expression of SMARCB1 or SMARCA4 proteins. Recent studies show that AT/RTs comprise three molecular subgroups, namely AT/RT-TYR, AT/RT-MYC and AT/RT-SHH. The subgroups show distinct expression patterns of genes involved in ciliogenesis, however, little is known about the functional roles of primary cilia in the biology of AT/RT. Here, we show that primary cilia are present across all AT/RT subgroups with specific enrichment in AT/RT-TYR patient samples. Furthermore, we demonstrate that primary ciliogenesis contributes to AT/RT biology in vitro and in vivo. Specifically, we observed a significant decrease in proliferation and clonogenicity following disruption of primary ciliogenesis in AT/RT cell line models. Additionally, apoptosis was significantly increased via the induction of STAT1 and DR5 signaling, as detected by proteogenomic profiling. In a Drosophila model of SMARCB1 deficiency, concomitant knockdown of several cilia-associated genes resulted in a substantial shift of the lethal phenotype with more than 20% of flies reaching adulthood. We also found significantly extended survival in an orthotopic xenograft mouse model of AT/RT upon disruption of primary ciliogenesis. Taken together, our findings indicate that primary ciliogenesis or its downstream signaling contributes to the aggressiveness of AT/RT and, therefore, may constitute a novel therapeutic target.

Development and validation of a triple-LED surgical loupe device for fluorescence-guided resections with 5-ALA.

OBJECTIVE: Fluorescence-guided resections performed using 5-aminolevulinic acid (5-ALA) have been studied extensively using the BLUE400 system. The authors introduce a triple-light-emitting diode (LED) headlight/loupe device for visualizing fluorescence, and compare this to the BLUE400 gold standard in order to assure similar and not more or less sensitive protoporphyrin-IX visualization. METHODS: The authors defined the spectral requirements for a triple-LED headlight/loupe device for reproducing the xenon-based BLUE400 module. The system consisted of a white LED (normal surgery), a 409-nm LED for excitation, a 450-nm LED for background illumination, and appropriate observation filters. The prototype's excitation and emission spectra, illumination and detection intensities, and spot homogeneity were determined. The authors further performed a prospectively randomized and blinded study for fluorescence assessments of fresh, marginal, fluorescing and nonfluorescing tumor samples comparing the LED/loupe device with BLUE400 in patients with malignant glioma treated with 20 mg/kg body weight 5-ALA. Tumor samples were immediately assessed in turn, both with a Kinevo and with a novel triple-LED/loupe device by different surgeons. RESULTS: Seven triple-LED/loupe devices were analyzed. Illumination intensities in the 409- and 450-nm range were comparable to BLUE400, with high spot homogeneity. Fluorescence intensities measured distally to microscope oculars/loupes were 9.9-fold higher with the loupe device. For validation 26 patients with malignant gliomas with 240 biopsies were analyzed. With BLUE400 results as the reference, sensitivity for reproducing fluorescence findings was 100%, specificity was 95%, positive predictive value was 98%, negative predictive value was 100%, and accuracy was 95%. This study reached its primary aim, with agreement in 226 of 240 (94.2%, 95% CI 0.904-0.968). CONCLUSIONS: The authors observed only minor differences regarding spectra and illumination intensities during evaluation. Fluorescence intensities available to surgeons were 9.9-fold higher with the loupe device. Importantly, the independent perception of fluorescence achieved using the new system and BLUE400 was statistically equivalent. The authors believe the triple-LED/loupe device to be a useful and safe option for surgeons who prefer loupes to the microscope for resections in appropriate patients.

Imaging-based prediction of histological clot composition from admission CT imaging.

BACKGROUND: Thrombus composition has been shown to be a major determinant of recanalization success and occurrence of complications in mechanical thrombectomy. The most important parameters of thrombus behavior during interventional procedures are relative fractions of fibrin and red blood cells (RBCs). We hypothesized that quantitative information from admission non-contrast CT (NCCT) and CT angiography (CTA) can be used for machine learning based prediction of thrombus composition. METHODS: The analysis included 112 patients with occlusion of the carotid-T or middle cerebral artery who underwent thrombectomy. Thrombi samples were histologically analyzed and fractions of fibrin and RBCs were determined. Thrombi were semi-automatically delineated in CTA scans and NCCT scans were registered to the same space. Two regions of interest (ROIs) were defined for each thrombus: small-diameter ROIs capture vessel walls and thrombi, large-diameter ROIs reflect peri-vascular tissue responses. 4844 quantitative image markers were extracted and evaluated for their ability to predict thrombus composition using random forest algorithms in a nested fivefold cross validation. RESULTS: Test set receiver operating characteristic area under the curve was 0.83 (95% CI 0.80 to 0.87) for differentiating RBC-rich thrombi and 0.84 (95% CI 0.80 to 0.87) for differentiating fibrin-rich thrombi. At maximum Youden-Index, RBC-rich thrombi were identified at 77% sensitivity and 74% specificity; for fibrin-rich thrombi the classifier reached 81% sensitivity at 73% specificity. CONCLUSIONS: Machine learning based analysis of admission imaging allows for prediction of clot composition. Perspectively, such an approach could allow selection of clot-specific devices and retrieval procedures for personalized thrombectomy strategies.

Small thrombus size, thrombus composition, and poor collaterals predict pre-interventional thrombus migration.

BACKGROUND: Different imaging characteristics such as clot burden score, collaterals, and pre-interventional thrombus migration are associated with functional outcome in patients with acute ischemic stroke. Moreover, histological thrombus composition is associated with pre-interventional thrombus migration. We hypothesized that smaller clots may more likely migrate and that collateral status in ischemic stroke patients may mediate this tendency of the clot to migrate. METHODS: In this prospective cohort of consecutive ischemic stroke patients, clot burden scores and collateral scores were rated and the retrieved thrombi were histologically analyzed. We then investigated the relationship between clot burden score, probability for thrombus migration, and collateral scores using mediation analysis. RESULTS: 163 patients are included of which 36 (22.1%) had a clot migration. Probability of thrombus migration was significantly associated with lower collateral scores (P<0.01), higher clot burden scores (P<0.01), shorter thrombi (P<0.01), and higher RBC count (P<0.01). In the mediator pathway, higher collateral scores were significantly associated with higher clot burden scores (P<0.01) and younger age (P=0.029). The total effect of an increase in clot burden score by one grade on thrombus migration is composed of the direct effect (+18%, P<0.01) and the collateral score-mediated indirect effect (-5%, P<0.01). CONCLUSIONS: Smaller, erythrocyte-rich thrombi tend to migrate more often. Good collaterals seem to have a considerable effect on limiting migration. This supports the hypothesis that larger clots have stronger adherence with the vessel wall and that good collaterals increase the counter pressure distal of the clot.

TSPO imaging-guided characterization of the immunosuppressive myeloid tumor microenvironment in patients with malignant glioma.

BACKGROUND: Tumor-associated microglia and macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) are potent immunosuppressors in the glioma tumor microenvironment (TME). Their infiltration is associated with tumor grade, progression, and therapy resistance. Specific tools for image-guided analysis of spatiotemporal changes in the immunosuppressive myeloid tumor compartments are missing. We aimed (i) to evaluate the role of fluorodeoxyglucose (18F)DPA-714* (translocator protein [TSPO]) PET-MRI in the assessment of the immunosuppressive TME in glioma patients, and (ii) to cross-correlate imaging findings with in-depth immunophenotyping. METHODS: To characterize the glioma TME, a mixed collective of 9 glioma patients underwent [18F]DPA-714-PET-MRI in addition to [18F]fluoro-ethyl-tyrosine (FET)-PET-MRI. Image-guided biopsy samples were immunophenotyped by multiparametric flow cytometry and immunohistochemistry. In vitro autoradiography was performed for image validation and assessment of tracer binding specificity. RESULTS: We found a strong relationship (r = 0.84, P = 0.009) between the [18F]DPA-714 uptake and the number and activation level of glioma-associated myeloid cells (GAMs). TSPO expression was mainly restricted to human leukocyte antigen D related-positive (HLA-DR+) activated GAMs, particularly to tumor-infiltrating HLA-DR+ MDSCs and TAMs. [18F]DPA-714-positive tissue volumes exceeded [18F]FET-positive volumes and showed a differential spatial distribution. CONCLUSION: [18F]DPA-714-PET may be used to non-invasively image the glioma-associated immunosuppressive TME in vivo. This imaging paradigm may also help to characterize the heterogeneity of the glioma TME with respect to the degree of myeloid cell infiltration at various disease stages. [18F]DPA-714 may also facilitate the development of new image-guided therapies targeting the myeloid-derived TME.

Validating a new generation filter system for visualizing 5-ALA-induced PpIX fluorescence in malignant glioma surgery: a proof of principle study.

BACKGROUND: The BLUE 400 filter system (Carl Zeiss Meditec, Oberkochen, Germany) has provided visualization of 5-ALA-induced fluorescence-guided surgery for more than 20 years. Nevertheless, constraints, e.g., limited background discrimination during hemostasis, obstruct fluency of surgery. A novel filter with improved background visualization was developed, requiring validation regarding fluorescence discrimination. The aim of this article is to determine diagnostic accuracy and perception of protoporphyrin IX (PpIX) discrimination of a novel filter system with higher background illumination (BLUE 400 AR) compared with the gold standard, BLUE 400. METHODS: A surgical microscope equipped with both BLUE 400 and BLUE 400 AR was used. Comparisons were performed on a biological basis and on the visual perception of margins. High-resolution images were compared during and after surgery by senior neurosurgeons. In a predefined biopsy algorithm, four biopsies per patient at tumor margins of PpIX fluorescence and adjacent brain were acquired using BLUE 400 AR only from regions intended for resection and assessed for cell count and density. RESULTS: Thirty-two patients with malignant gliomas were included in this study. BLUE 400 AR markedly enhanced the brightness of the surgical field, allowing superior discrimination of brain anatomy. A total of 128 biopsies from fluorescence margins were collected. Positive predictive value (PPV) was 98.44% (95% CI, 90.06-99.77%) for malignant glioma. Residual median cell density in non-fluorescent tissue was 13% (IQR 13 to 31). Perception of the location of fluorescent margins on HD images was equivalent for both filter combinations. CONCLUSIONS: BLUE 400 AR demonstrated superior background compared with conventional BLUE 400 in malignant glioma surgery but comparable fluorescence margins and PPV. Therefore, BLUE 400 AR can be considered safe and effective in supporting malignant glioma surgery.

Heterotopic Neuroglial Tissue in Sphenoid Ridge.

BACKGROUND: Extracerebral neuroglial heterotopias are rare manifestations of cerebral tissue outside the brain whose most common form is the so-called nasal glioma. In this case report we illustrate the first case of heterotopic neuroglial tissue within the bone of the skull. CASE DESCRIPTION: Our patient underwent surgery for a sphenoid ridge meningioma. Aside from the expected meningioma, histopathologic examination showed a small amount of intraosseous heterotopic neuroglial tissue. CONCLUSIONS: The pathogenesis of cerebral heterotopias is diverse. Most of the midline lesions are probably residuals of former meningoencephaloceles. The pathogenesis of extracranial nonmidline lesions is more questionable. Their cause might be a former trauma, inflammatory disease, or surgery. Another option is that they represent primary neuroglial heterotopias, as it is supposed for manifestations of the lung. The coexistence of a heterotopia and a meningioma in this case is probably a coincidence. It is also debatable whether the broad tumor extension within the bone and/or the heterotopia might go back to alterations of the bone structure.

Identification of genes functionally involved in the detrimental effects of mutant histone H3.3-K27M in Drosophila melanogaster.

BACKGROUND: Recurrent specific mutations in evolutionarily conserved histone 3 (H3) variants drive pediatric high-grade gliomas (HGGs), but little is known about their downstream effects. The aim of this study was to identify genes involved in the detrimental effects of mutant H3.3-K27M, the main genetic driver in lethal midline HGG, in a transgenic Drosophila model. METHODS: Mutant and wild-type histone H3.3-expressing flies were generated using a φC31-based integration system. Genetic modifier screens were performed by crossing H3.3-K27M expressing driver strains and 194 fly lines expressing short hairpin RNA targeting genes selected based on their potential role in the detrimental effects of mutant H3. Expression of the human orthologues of genes with functional relevance in the fly model was validated in H3-K27M mutant HGG. RESULTS: Ubiquitous and midline glia-specific expression of H3.3-K27M but not wild-type H3.3 caused pupal lethality, morphological alterations, and decreased H3K27me3. Knockdown of 17 candidate genes shifted the lethal phenotype to later stages of development. These included histone modifying and chromatin remodeling genes as well as genes regulating cell differentiation and proliferation. Notably, several of these genes were overexpressed in mutant H3-K27M mutated HGG. CONCLUSIONS: Rapid screening, identification, and validation of relevant targets in "oncohistone" mediated pathogenesis have proven a challenge and a barrier to providing novel therapies. Our results provide further evidence on the role of chromatin modifiers in the genesis of H3.3-K27M. Notably, they validate Drosophila as a model system for rapid identification of relevant genes functionally involved in the detrimental effects of H3.3-K27M mutagenesis.

LA-ICP-MS/MS improves limits of detection in elemental bioimaging of gadolinium deposition originating from MRI contrast agents in skin and brain tissues.

A novel analytical method to detect the retention of gadolinium from contrast agents for magnetic resonance imaging (MRI) in tissue samples of patients is presented. It is based on laser ablation - inductively coupled plasma - triple quadrupole - mass spectrometry (LA-ICP-MS/MS). Both Gd and P were monitored with a mass shift of +16, corresponding to mono-oxygenated species, as well as Zn, Ca, and Fe on-mass. This method resulted in a significantly reduced background and improved limits of detection not only for phosphorus, but also for gadolinium. These improvements were essential to perform elemental bioimaging with improved resolution of 5 µm x 5 µm, allowing the detection of small Gd deposits in fibrotic skin and brain tumour tissue with diameters of approximately 50 µm. Detailed analyses of these regions revealed that most Gd was accompanied with P and Ca, indicating co-precipitation.

Functional relevance of genes predicted to be affected by epigenetic alterations in atypical teratoid/rhabdoid tumors.

PURPOSE: Atypical teratoid/rhabdoid tumor (ATRT) is a highly malignant brain tumor predominantly arising in infants. Mutations of SWI/SNF chromatin remodeling complex members SMARCB1/INI1 or (rarely) SMARCA4/Brg1 are the sole recurrent genetic lesions. Epigenetic studies revealed a large number of genes predicted to be affected by differential histone modifications in ATRT, but the role of these genes in the biology of ATRT remains uncertain. We therefore aimed at exploring the role of these genes in the detrimental effects of SMARCB1-deficiency. METHODS: The functional relevance of 1083 genes predicted to be affected by epigenetic alterations in ATRT was examined in vivo using a Drosophila melanogaster model of SMARCB1-deficiency. Human orthologues of genes whose knockdown modified the phenotype in the Gal4-UAS fly model were further examined in ATRT samples and SMARCB1-deficient rhabdoid tumor cells. RESULTS: Knockdown of Snr1, the fly orthologue of SMARCB1, resulted in a lethal phenotype and epigenetic alterations in the fly model. The lethal phenotype was shifted to later stages of development upon additional siRNA knockdown of 89 of 1083 genes screened in vivo. These included TGF-beta receptor signaling pathway related genes, e.g. CG10348, the fly orthologue of transcriptional regulator PRDM16. Subsequently, PRDM16 was found to be over-expressed in ATRT samples and knockdown of PRDM16 in SMARCB1-deficient rhabdoid tumor cells reduced proliferation. CONCLUSIONS: These results suggest that a subset of genes affected by differential histone modification in ATRT is involved in the detrimental effects of SMARCB1-deficiency and also relevant in the biology of ATRT.

Complementary Molecular and Elemental Mass-Spectrometric Imaging of Human Brain Tumors Resected by Fluorescence-Guided Surgery.

Fluorescence-guided surgery (FGS) has been established as a powerful technique for glioblastoma resection. After oral application of the prodrug 5-aminolevulinic acid (5-ALA), protoporphyrin IX (PpIX) is formed as an intermediate of the heme-biosynthesis cascade and accumulates within the tumor. By intraoperative fluorescence microscopy, the specific PpIX fluorescence can be used to differentiate the tumor from healthy brain tissue. To investigate possible limitations of fluorescence diagnosis, the complementary use of molecular and elemental mass-spectrometry imaging (MSI) is presented. Matrix-assisted laser-desorption-ionization mass spectrometry (MALDI-MS) is used to examine the distribution of PpIX and heme b in human brain tumors. MALDI-MS/MS imaging is performed to validate MS data and improve the signal-to-noise ratio (S/N). Comparing the imaging results with histological evaluation, increased PpIX accumulation in areas of high tumor-cell density is observed. Heme b accumulation are only found in areas of blood vessels and hemorrhage, confirming the hampered transformation from PpIX to heme b in glioblastoma tissue. Investigation of non-neoplastic brain tissue and glioblastoma resected without external 5-ALA administration as control samples with true-negative fluorescence verified the absence of PpIX accumulation. Analysis of necrotic tumor tissue and gliosarcoma, one rare type of glioma appearing nonfluorescent during FGS, as case examples with false-negative-fluorescence diagnosis, revealed the absence of significant amounts of PpIX, indicating an impairment of PpIX formation. Molecular analysis is complemented by quantitative laser ablation-inductively coupled plasma (LA-ICP) MSI correlating heme b and Fe distribution. Mathematical pixel-by-pixel correlation of molecular and elemental data revealed a positive correlation with heteroscedasticity for the spatially resolved heme b signal intensities and Fe concentrations.

Gadolinium-based contrast agents induce gadolinium deposits in cerebral vessel walls, while the neuropil is not affected: an autopsy study.

Recent studies showed gadolinium depositions following serial administrations of gadolinium-based contrast agents (GBCAs) for magnetic resonance imaging examinations in various parts of the brain with the dentate nucleus (DN) being most affected. Even though no clinical correlates of the deposits are known yet, an intensive debate developed if this might be harmful. The aim of the current study was to specify the gadolinium distribution in brain tissue of patients who received serial injections of GBCAs in the low-µm range and to explore any potential pathological tissue changes caused by gadolinium deposits. Thirteen autopsy cases-eight receiving GBCA administrations, five serving as controls-were identified and analyzed. For all patients, total gadolinium quantification after acidic digestion by means of inductively coupled plasma-mass spectrometry (ICP-MS) was performed. Six cases were utilized for the spatially resolved quantification of gadolinium within the cerebellum and the basal ganglia by means of high-resolution laser ablation (LA)-ICP-MS. Histopathological and immunohistochemical examinations were performed to determine tissue reactions. LA-ICP-MS revealed gadolinium depositions in the walls of small blood vessels of the DN in all GBCA exposed patients, while no gadolinium was found in the control group. Additionally, the detection of phosphorus and metals like copper, zinc and iron provides evidence that transmetalation reactions might have occurred. No significant pathological changes of the brain tissue in the vicinity of the DN with respect to micro-/astrogliosis and neuronal loss were found in any of the patients. This notably holds true even for a patient who died from nephrogenic systemic fibrosis exhibiting extremely high gadolinium concentrations within the DN. The findings show that gadolinium depositions in the brain are restricted to blood vessel walls, while the neuropil is spared and apparent cellular reactions are absent.

Visualizing protoporphyrin IX formation in the dura tail of meningiomas by mass spectrometry imaging.

BACKGROUND: The advantages of 5-aminolevulinacid (5-ALA)-induced fluorescence-guided surgery in meningiomas are increasingly discussed. In this context, despite detectable tumor tissue in histopathologial analyses, no fluorescence was shown at the dura tail using the standard operating microscope. Thus, 5-ALA metabolism in this surgically important site remains unknown but needs to be elucidated when further evaluating indications of fluorescence-guided surgery in meningiomas. METHOD: We here present the spatially resolved identification of protoporphyrin IX (PpIX) in sphenoid ridge meningioma cryosections from a patient who underwent fluorescence-guided microsurgery using molecular imaging analysis by matrix-assisted laser desorption/ionization tandem mass spectrometry (MALDI-MS/MS). RESULTS: Despite a strong fluorescence of the main tumor, no fluorescence could be detected at the dura tail using the standard operating microscope (blue-light, 405 nm). However, histopathological analyses clearly showed meningioma tissue. Remarkably, MALDI-MS/MS analysis revealed PpIX formation also at the non-fluorescing dura tail. However, no PpIX was detected in the tumor free dura mater. CONCLUSION: MALDI-MS/MS visualized a selective accumulation of PpIX within the tumor tissue including the dura tail. Thus, absence of fluorescence in the dura tail as visualized by the operating microscope is not caused by the lack of PpIX formation.

Ischemic Stroke: Histological Thrombus Composition and Pre-Interventional CT Attenuation Are Associated with Intervention Time and Rate of Secondary Embolism.

BACKGROUND AND PURPOSE: The introduction of stent retrievers has made the complete extraction and histological analysis of human thrombi possible. A number of large randomized trials have proven the efficacy of thrombectomy for ischemic stroke; however, thrombus composition could have an impact on the efficacy and risk of the intervention. We therefore investigated the impact of histologic thrombus features on interventional outcome and procedure-related embolisms. For a pre-interventional estimation of histologic features and outcome parameters, we assessed the pre-interventional CT attenuation of the thrombi. METHODS: We prospectively included all consecutive patients with occlusion of the middle cerebral artery who underwent thrombectomy between December 2013 and February 2016 at our university medical center. Samples were histologically analyzed (H&E, Elastica van Gieson, Prussian blue); additionally, immunohistochemistry for CD3, CD20, and CD68/KiM1P was performed. Main thrombus components (fibrin, erythrocytes, and white blood cells) were determined and compared to intervention time, frequency of secondary embolisms, as well as additional clinical and interventional parameters. Additionally, we assessed the pre-interventional CT attenuation of the thrombi in relation to the unaffected side (rHU) and their association with histologic features. RESULTS: One hundred eighty patients were included; of these, in 168 patients (93.4%), complete recanalization was achieved and 27 patients (15%) showed secondary embolism in the control angiogram. We observed a significant association of high amounts of fibrin (p < 0.001), low percentage of red blood cells (p < 0.001), and lower rHU (p < 0.001) with secondary embolism. Higher rHU values were significantly associated with higher amounts of fibrin (p ≤ 0.001) and low percentage of red blood cells (p ≤ 0.001). Additionally, high amounts of fibrin were associated with longer intervention times (p ≤ 0.001), whereas thrombi with high amounts of erythrocytes correlated with shorter intervention times (p ≤ 0.001). ROC analysis revealed reliable prediction of secondary embolisms for low rHU (AUC = 0.746; p ≤ 0.0001), low amounts of RBC (AUC = 0.764; p ≤ 0.0001), and high amounts of fibrin (AUC = 0.773; p ≤ 0.0001). CONCLUSIONS: Fibrin-rich thrombi with low erythrocyte percentage are significantly associated with longer intervention times. Embolisms in the thrombectomy process occur more often in thrombi with a small fraction of red blood cells and a low CT-density, suggesting a higher fragility of these thrombi.

Multimodal Imaging of Patients With Gliomas Confirms 11C-MET PET as a Complementary Marker to MRI for Noninvasive Tumor Grading and Intraindividual Follow-Up After Therapy.

The value of combined L-( methyl-[11C]) methionine positron-emitting tomography (MET-PET) and magnetic resonance imaging (MRI) with regard to tumor extent, entity prediction, and therapy effects in clinical routine in patients with suspicion of a brain tumor was investigated. In n = 65 patients with histologically verified brain lesions n = 70 MET-PET and MRI (T1-weighted gadolinium-enhanced [T1w-Gd] and fluid-attenuated inversion recovery or T2-weighted [FLAIR/T2w]) examinations were performed. The computer software "visualization and analysis framework volume rendering engine (Voreen)" was used for analysis of extent and intersection of tumor compartments. Binary logistic regression models were developed to differentiate between World Health Organization (WHO) tumor types/grades. Tumor sizes as defined by thresholding based on tumor-to-background ratios were significantly different as determined by MET-PET (21.6 ± 36.8 cm3), T1w-Gd-MRI (3.9 ± 7.8 cm3), and FLAIR/T2-MRI (64.8 ± 60.4 cm3; P < .001). The MET-PET visualized tumor activity where MRI parameters were negative: PET positive tumor volume without Gd enhancement was 19.8 ± 35.0 cm3 and without changes in FLAIR/T2 10.3 ± 25.7 cm3. FLAIR/T2-MRI visualized greatest tumor extent with differences to MET-PET being greater in posttherapy (64.6 ± 62.7 cm3) than in newly diagnosed patients (20.5 ± 52.6 cm3). The binary logistic regression model differentiated between WHO tumor types (fibrillary astrocytoma II n = 10 from other gliomas n = 16) with an accuracy of 80.8% in patients at primary diagnosis. Combined PET and MRI improve the evaluation of tumor activity, extent, type/grade prediction, and therapy-induced changes in patients with glioma and serve information highly relevant for diagnosis and management.

The Simpson grading in meningioma surgery: does the tumor location influence the prognostic value?

In meningiomas, location-specific differences of the prognostic value of the Simpson classification are sparsely investigated but can influence strategy of surgery. We therefore compared the prognostic value of the Simpson classification in different tumor locations. Progression was compared with Simpson grade in 826 meningioma patients (median age 58 years, female:male ratio 2.4) in location-specific uni- and multivariate analyses. Simpson grade strongly correlated with tumor location (p < .001). Within a median follow-up of 50 months, recurrence was observed in 107 of 803 patients (13%). In general, increasing Simpson grade (p = .002) and subtotal resection (STR, ≥grade III) were correlated with tumor recurrence [hazard ratio (HR): 1.87; p = .004]. In 268 convexity meningiomas, frequency of tumor recurrence correlated with Simpson grade (p = .034). Risk of recurrence was similar after grade I and II resections, tended to increase after grade III (HR: 2.35; p = .087) but was higher after grade IV resections (HR: 7.35; p = .003). Risk of recurrence was higher after STR (HR: 4.21; p = .001) than after gross total resection (GTR, ≤grade II). Contrarily, increasing Simpson grade and STR were not correlated with progression in 102 falx, 38 posterior fossa and nine intraventricular meningiomas. In 325 skull base lesions, risk of recurrence was similar after GTR and STR (p = .198) and was only increased after grade IV resections (HR: 3.26; p = .017). Simpson grading and extent of resection were not equally prognostic in all locations. Lower impact of extent of resection should be considered during surgery for skull base, posterior fossa and falx meningiomas.

SMAD dependent signaling plays a detrimental role in a fly model of SMARCB1-deficiency and the biology of atypical teratoid/rhabdoid tumors.

Atypical teratoid/rhabdoid tumors (ATRT) are highly malignant brain tumors arising in young children. The majority of ATRT is characterized by inactivation of the chromatin remodeling complex member SMARCB1 (INI1/hSNF5). Little is known, however, on downstream pathways involved in the detrimental effects of SMARCB1 deficiency which might also represent targets for treatment. Using Drosophila melanogaster and the Gal4-UAS system, modifier screens were performed in order to identify the role of SMAD dependent signaling in the lethal phenotype associated with knockdown of snr1, the fly homolog of SMARCB1. Expression and functional role of human homologs was next investigated in ATRT tumor samples and SMARCB1-deficient rhabdoid tumor cells. The lethal phenotype associated with snr1 knockdown in Drosophila melanogaster could be shifted to later stages of development upon additional knockdown of several decapentaplegic pathway members including Smox, and Med. Similarly, the transforming growth factor beta (TGFbeta) receptor type I kinase inhibitor SB431542 ameliorated the detrimental effect of snr1 knockdown in the fruit fly. Examination of homologs of candidate decapentaplegic pathway members in human SMARCB1-deficent ATRT samples revealed SMAD3 and SMAD6 to be over-expressed. In SMARCB1-deficent rhabdoid tumor cells, siRNA-mediated silencing of SMAD3 or SMAD6 expression reduced TGFbeta signaling activity and resulted in decreased proliferation. Similar results were obtained upon pharmacological inhibition of TGFbeta signaling using SB431542. Our data suggest that SMAD dependent signaling is involved in the detrimental effects of SMARCB1-deficiency and provide a rationale for the investigation of TGFbeta targeted treatments in ATRT.

Cribriform neuroepithelial tumor: molecular characterization of a SMARCB1-deficient non-rhabdoid tumor with favorable long-term outcome.

Rhabdoid phenotype and loss of SMARCB1 expression in a brain tumor are characteristic features of atypical teratoid/rhabdoid tumors (ATRT). Rare non-rhabdoid brain tumors showing cribriform growth pattern and SMARCB1 loss have been designated cribriform neuroepithelial tumor (CRINET). Small case series suggest that CRINETs may have a relatively favorable prognosis. However, the long-term outcome is unclear and it remains uncertain whether CRINET represents a distinct entity or a variant of ATRT. Therefore, 10 CRINETs were clinically and molecularly characterized and compared with 10 ATRTs of each of three recently described molecular subgroups (i.e. ATRT-TYR, ATRT-SHH and ATRT-MYC) using Illumina Infinium HumanMethylation450 arrays, FISH, MLPA, and sequencing. Furthermore, outcome was compared to a larger cohort of 27 children with ATRT-TYR. Median age of the 6 boys and 4 girls harboring a CRINET was 20 months. On histopathological examination, all CRINETs demonstrated a cribriform growth pattern and distinct tyrosinase staining. On unsupervised cluster analysis of methylation data, all CRINETs examined exclusively clustered within the ATRT-TYR molecular subgroup. As ATRT-TYR, CRINETs mainly showed large heterozygous 22q deletions (9/10) and SMARCB1 mutations of the other allele. In two patients, SMARCB1 mutations were also present in the germline. Estimated mean overall survival in patients with CRINETs was 125 months (95% confidence interval 100-151 months) as compared to only 53 (33-74) months in patients with ATRTs of the ATRT-TYR subgroup (Log-Rank P < 0.05). In conclusion, CRINET represents a SMARCB1-deficient non-rhabdoid tumor, which shares molecular similarities with the ATRT-TYR subgroup but has distinct histopathological features and favorable long-term outcome.